Have not used Node Red in production and only played with it briefly, but n8n is more of a Zapier replacement whereas Node Red I believe is more of an IoT automation platform.

n8n is made so that you can set it up and give your staff access and they can manage their own workflows (like "when a customer opens a support ticket, update their Salesforce record to increment the number of tickets they have opened").

It's clearly aimed at non technical users being able to develop their own solutions to problems (for better or for worse), more so than Windmill which is made for developers to solve their own problems or develop solutions that non-technical people can use. Node Red if I remember correctly is more heavily weighted toward real time events for dev (especially hardware/IoT dev) use than "let the support team manage their own workflows for routing customer complaints"